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Pennsylvania CDL: General Knowledge

Selected knowledge practice, not a complete licensing course or practical training.

Pennsylvania CDL General Knowledge

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Question 1 of 100
  1. 1. A mechanic has repaired a defect on an interstate commercial vehicle. Before driving, who must still be satisfied that its required equipment works safely?
  2. 2. Which items should a commercial driver monitor during a trip for signs of trouble?
  3. 3. Under federal rules for an interstate commercial truck, what minimum tread depth is required in the front tires' major grooves?
  4. 4. Under federal rules for an interstate bus, which tires are prohibited on its front wheels?
  5. 5. What can rust around a commercial vehicle’s wheel nuts indicate?
  6. 6. Why is excessive steering-wheel play a serious inspection defect?
  7. 7. Which is a federal warning-equipment option for an interstate commercial vehicle?
  8. 8. Why should you follow a consistent sequence when inspecting your commercial vehicle?
  9. 9. What is the principal method for controlling speed on a long downgrade?
  10. 10. When should a commercial driver select the proper low gear for a downgrade?
  11. 11. How should speed be chosen when fog or darkness limits the view ahead?
  12. 12. Under the handbook length rule below 40 mph, what is the minimum following time for a 50-foot commercial vehicle?
  13. 13. Under the handbook's vehicle-length following rule, what extra time should be added above 40 mph?
  14. 14. How should a commercial driver respond to a vehicle following too closely?
  15. 15. Why might an empty cargo van require more overhead clearance than the same van when loaded?
  16. 16. When a large vehicle needs extra room to complete a right turn, what should the driver avoid doing at the start?
  17. 17. You take an interstate truckload that the shipper loaded. Who must still recognize overloads or unsafe weight balance?
  18. 18. On an interstate truck trip, when must you first recheck an accessible, unsealed load's securement?
  19. 19. On an interstate truck trip, after the initial check of an accessible, unsealed load, when must you next recheck securement?
  20. 20. What does a single vehicle’s gross vehicle weight rating (GVWR) represent?
  21. 21. Where should the heaviest cargo generally be placed to reduce rollover risk?
  22. 22. What can result from placing too little weight on the front axle?
  23. 23. Under federal rules for an interstate truck load, what minimum aggregate working load limit must tiedowns securing an article provide?
  24. 24. An interstate truck carries a 7-foot article under the general federal tiedown rule. It is not blocked against forward movement. What is the minimum tiedown count?
  25. 25. Why should a driver check cargo covers in the mirrors while traveling?
  26. 26. You must back into an unfamiliar loading space. What should you do before beginning the maneuver?
  27. 27. While backing slowly, you become unsure whether the right rear corner will clear an obstacle. What is the safest next step?
  28. 28. Before backing with a helper, which signal should you both agree on?
  29. 29. The drive wheels begin spinning as you accelerate from a stop on a snowy road. What response does the handbook recommend?
  30. 30. You are approaching a curve in a commercial vehicle with a manual transmission. When should you reduce speed and select the appropriate lower gear?
  31. 31. A vehicle appears small and distant in your convex mirror. What should you remember before judging the available gap?
  32. 32. Before a trip with a trailer, which position allows an accurate check of mirror adjustment?
  33. 33. You are looking 12 to 15 seconds ahead as recommended for commercial driving. How should you also monitor the nearer road?
  34. 34. What is the safest way to make routine mirror checks while traveling?
  35. 35. Before departure, why should you secure loose tools and other articles in the cab?
  36. 36. A following driver wants to pass your truck. Should you wave them around as a guarantee that the road is clear?
  37. 37. For an interstate CMV breakdown that requires emergency warning devices, what is the latest deadline for placing them?
  38. 38. An interstate truck breaks down on a straight divided highway with clear sightlines. What federal warning-device layout applies?
  39. 39. An interstate truck breaks down on a straight rural two-way highway. Why place required warning devices both ahead and behind?
  40. 40. At dusk in rain, are identification and clearance lights alone sufficient to make your truck visible?
  41. 41. You keep your hands on the wheel but become absorbed in a stressful conversation. What type of distraction can this create?
  42. 42. When is the best time to program the route into your navigation system?
  43. 43. A car ahead drifts within its lane while its driver looks down repeatedly. How should you react?
  44. 44. An aggressive driver tries to provoke you. What is the safer response?
  45. 45. Snow covers the truck's mirrors and side windows before departure. What is needed for a safe start?
  46. 46. Why is a leaking exhaust especially dangerous when the cab windows are closed?
  47. 47. After water enters a truck’s brakes, what behavior can occur?
  48. 48. A properly inflated tire’s pressure rises during hot-weather operation. Should you bleed air to its cold-pressure reading?
  49. 49. During a hot-weather stop, a tire is too hot to touch. What does the handbook direct you to do?
  50. 50. When is it safe to open the pressurized radiator system for a coolant check?
  51. 51. Dark patches of tar have risen to the road surface in extreme heat. What hazard should you expect?
  52. 52. How should a manual-transmission truck cross railroad tracks?
  53. 53. One train has passed a crossing with two tracks. What must you check before proceeding?
  54. 54. A railroad crossing has no active lights or gates. What does that mean for your decision?
  55. 55. Why is listening for a horn alone an unsafe crossing check?
  56. 56. The front wheels slide and the truck continues straight despite steering input. What should you avoid?
  57. 57. Excessive braking has locked the rear drive wheels of a truck without effective ABS intervention. What is the first recovery action?
  58. 58. After a collision, you are uninjured and able to act. What is an immediate priority?
  59. 59. You stop to help at a collision in which your truck was not involved. Where should you park?
  60. 60. Smoke indicates a vehicle fire while you are driving. Where should you stop if you can safely move off the road?
  61. 61. Why should you avoid opening the hood during an engine fire?
  62. 62. Smoke comes from a closed box trailer, and the cargo may be hazardous. Should you open its doors to investigate?
  63. 63. For a small fire you are trained to tackle safely, with the correct extinguisher and a clear escape path, where should you aim?
  64. 64. You do not know which extinguishing agent is safe for the burning cargo. What should you do?
  65. 65. A B:C extinguisher is intended for which hazards?
  66. 66. What is the purpose of blocks secured snugly around cargo?
  67. 67. What does bracing between upper cargo and the compartment structure help prevent?
  68. 68. Your load uses a front-end header board for forward restraint. Why inspect that board before departure?
  69. 69. An interstate truck carries a sealed load that you are ordered not to open. Which duty still remains?
  70. 70. What makes a dry-bulk tank load demanding in a sharp curve?
  71. 71. Why is suspended meat cargo a special concern on an off-ramp?
  72. 72. How can live animals affect trailer stability?
  73. 73. Before moving a load that exceeds ordinary legal size or weight limits, what arrangements should you check?
  74. 74. What does axle weight measure?
  75. 75. Your load is within the legal maximum. Does that guarantee it is safe for bad weather or a mountain route?
  76. 76. How should you determine suitable shift points for an unfamiliar commercial vehicle?
  77. 77. Why does the handbook advise turning a retarder off on a slippery road?
  78. 78. An approaching driver leaves bright lights on. What should you do?
  79. 79. Why clean both sides of the windshield before a night trip?
  80. 80. Your eyelids are heavy and you are struggling to stay alert. What is the safe response?
  81. 81. You see dense fog ahead while approaching a safe truck stop. What is the preferable choice?
  82. 82. Why should you avoid using another vehicle’s taillights as your only guide through fog?
  83. 83. When should you learn how to fit the chains carried for your drive tires?
  84. 84. Which combination matters when selecting a safe descent speed?
  85. 85. Your truck’s brakes have failed on a downgrade and an escape ramp is available. What should you do?
  86. 86. A hydraulic service-brake pedal goes to the floor. Which action may briefly restore hydraulic pressure?
  87. 87. A truck tire fails, but there is no immediate collision ahead. What is the initial response?
  88. 88. Does buying a cold medicine without a prescription prove it is safe before commercial driving?
  89. 89. A cardboard box in your lane looks empty. What should you remember when planning how to avoid it?
  90. 90. Why should a commercial driver keep required hazardous-material shipping papers easy to find?
  91. 91. Your vehicle was operating normally yesterday. What inspection is needed for the next trip?
  92. 92. A hot engine has a see-through coolant reservoir with level markings. How can you check the level without opening the hot system?
  93. 93. An interstate truck breaks down on a highway shoulder. Which lights should you switch on immediately?
  94. 94. In its basic steering-defect guidance, what amount of steering-wheel free play does the Pennsylvania CDL manual warn can make steering difficult?
  95. 95. A freight container is designed to transfer between a truck chassis, a train and a ship. What kind of container is it?
  96. 96. Why should a driver not use water on burning gasoline or energized electrical equipment?
  97. 97. Which three distances make up the basic stopping-distance model in Pennsylvania CDL manual section 2.6.1?
  98. 98. A newer streamlined truck climbed a hill in a relatively high gear. Should you automatically use that same gear to descend?
  99. 99. Two legal parking spaces are equally suitable for your truck. One allows a forward exit; the other requires backing into traffic. Which is preferable?
  100. 100. Why check the rated capacity of a coupling device before assigning a load?
Review all 100 questions with answers

  1. A mechanic has repaired a defect on an interstate commercial vehicle. Before driving, who must still be satisfied that its required equipment works safely?

    Correct answer: The driver

    The driver's before-driving responsibility remains even when a mechanic has carried out repairs. Do not operate with an unsafe defect.

    Source: 49 CFR 392.7(a), driver satisfaction with required equipment before operation; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.5, Seven-step Inspection Method > Step 7: unsafe defects; printed p. 2-10, physical PDF page 39. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=39 ↗

  2. Which items should a commercial driver monitor during a trip for signs of trouble?

    Correct answer: Gauges, sight, sound, smell, and feel

    Trip inspection includes watching gauges and using the senses to detect developing problems.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.2, Types of Vehicle Inspection > During a Trip; printed p. 2-2, physical PDF page 31. ↗

  3. Under federal rules for an interstate commercial truck, what minimum tread depth is required in the front tires' major grooves?

    Correct answer: 4/32 inch

    Front tires on buses, trucks and truck tractors need at least 4/32 inch in major grooves; the general minimum for other tires is 2/32 inch. Do not measure on tie bars, humps or fillets.

    Source: 49 CFR 393.75(b)-(c), front-tire tread and excluded tie bars, humps and fillets; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.3, What to Look For > Tire Problems; printed p. 2-2, physical PDF page 31. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=31 ↗

  4. Under federal rules for an interstate bus, which tires are prohibited on its front wheels?

    Correct answer: Regrooved, recapped, or retreaded tires

    A bus may not use regrooved, recapped, or retreaded tires on its front wheels.

    Source: 49 CFR 393.75(d), bus front tires; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.3, What to Look For > Tire Problems: bus front tires; printed p. 2-2, physical PDF page 31. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=31 ↗

  5. What can rust around a commercial vehicle’s wheel nuts indicate?

    Correct answer: The nuts may be loose

    Rust trails around wheel nuts can be evidence of movement and looseness.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.3, What to Look For > Wheel and Rim Problems; printed p. 2-2, physical PDF page 31. ↗

  6. Why is excessive steering-wheel play a serious inspection defect?

    Correct answer: It can make the vehicle difficult to steer

    Excessive play can prevent precise steering control and must be investigated.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.3, What to Look For > Steering System Defects; printed p. 2-3, physical PDF page 32. ↗

  7. Which is a federal warning-equipment option for an interstate commercial vehicle?

    Correct answer: Three red reflective warning triangles

    Three approved bidirectional reflective triangles are a federal warning-equipment option. They must meet the applicable equipment standard; ordinary lights do not replace them.

    Source: 49 CFR 393.95(f)(1), three conforming bidirectional emergency reflective triangles; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.5, Seven-step Inspection Method > Check Emergency Equipment; printed p. 2-7, physical PDF page 36. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=36 ↗

  8. Why should you follow a consistent sequence when inspecting your commercial vehicle?

    Correct answer: It reduces the chance of overlooking a component

    Following the same inspection method helps you remember the checks and notice problems before driving.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.5, Seven-step Inspection Method > Method of Inspection; printed p. 2-5, physical PDF page 34. ↗

  9. What is the principal method for controlling speed on a long downgrade?

    Correct answer: Engine braking in a suitable low gear

    Selecting a low gear before descending lets engine braking control speed while preserving the service brakes.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.16.1, Select a Safe Speed: engine braking; printed p. 2-40, physical PDF page 69. ↗

  10. When should a commercial driver select the proper low gear for a downgrade?

    Correct answer: Before starting down the grade

    The gear must be selected before descending because shifting later may be unsafe or impossible.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.16.2, Select the Right Gear Before Starting Down the Grade; printed p. 2-40, physical PDF page 69. ↗

  11. How should speed be chosen when fog or darkness limits the view ahead?

    Correct answer: So the vehicle can stop within the visible distance

    A driver must always be able to stop within the distance that can be seen clearly.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.6.4, Speed and Distance Ahead; printed p. 2-20, physical PDF page 49. ↗

  12. Under the handbook length rule below 40 mph, what is the minimum following time for a 50-foot commercial vehicle?

    Correct answer: 5 seconds

    The basic minimum is one second per 10 feet of vehicle length: five seconds for 50 feet. Leave more space when road, traffic, or weather conditions require it.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.7.1, Space Ahead > How Much Space?; printed p. 2-22, physical PDF page 51. ↗

  13. Under the handbook's vehicle-length following rule, what extra time should be added above 40 mph?

    Correct answer: One additional second

    Start with at least one second per 10 feet of vehicle length, then add one second above 40 mph. Poor road or weather conditions require more space.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.7.1, Space Ahead > How Much Space?; printed p. 2-22, physical PDF page 51. ↗

  14. How should a commercial driver respond to a vehicle following too closely?

    Correct answer: Increase the space ahead and avoid sudden changes

    More room ahead reduces the need for sudden braking and gives the tailgater an opportunity to pass.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.7.2, Space Behind > Dealing with Tailgaters Safely; printed p. 2-22, physical PDF page 51. ↗

  15. Why might an empty cargo van require more overhead clearance than the same van when loaded?

    Correct answer: Its suspension may sit higher when empty

    Removing cargo can raise the vehicle, so a clearance that worked while loaded may no longer be sufficient.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.7.4, Space Overhead; printed p. 2-23, physical PDF page 52. ↗

  16. When a large vehicle needs extra room to complete a right turn, what should the driver avoid doing at the start?

    Correct answer: Swinging wide to the left

    A left swing can invite a following vehicle to pass on the right and enter the truck’s turning path.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.7.6, Space for Turns > Right Turns; printed p. 2-23, physical PDF page 52. ↗

  17. You take an interstate truckload that the shipper loaded. Who must still recognize overloads or unsafe weight balance?

    Correct answer: The driver

    The driver has cargo-safety responsibilities even when someone else loaded the truck. Federal sealed or impracticable-to-inspect load exceptions are limited inspection exceptions, not permission to ignore unsafe loading.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), Section 3 introduction: driver cargo responsibilities; printed p. 3-1, physical PDF page 83. Corroboration/qualification: 49 CFR 392.9(a), (b)(1), and (b)(4), https://www.ecfr.gov/current/title-49/subtitle-B/chapter-III/subchapter-B/part-392/subpart-A/section-392.9, reviewed 2026-09-12. ↗

  18. On an interstate truck trip, when must you first recheck an accessible, unsealed load's securement?

    Correct answer: Within the first 50 miles

    The federal rule requires inspection within the first 50 miles and correction of insecure loading. It separately excepts sealed loads the driver is ordered not to open and loads that cannot practicably be inspected.

    Source: 49 CFR 392.9(b)(2) and (b)(4), initial cargo reinspection and exceptions; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.1, Inspecting Cargo > After Starting; printed p. 3-1, physical PDF page 83. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=83 ↗

  19. On an interstate truck trip, after the initial check of an accessible, unsealed load, when must you next recheck securement?

    Correct answer: At a duty-status change, 3 hours of driving, or 150 miles, whichever occurs first

    Recheck securement at the first of these events: a change of duty status, three driving hours, or 150 miles. Make needed adjustments before continuing.

    Source: 49 CFR 392.9(b)(3)(i)-(iii) and (b)(4), reinspection triggers and exceptions; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.1, Inspecting Cargo > Re-check; printed p. 3-1, physical PDF page 83. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=83 ↗

  20. What does a single vehicle’s gross vehicle weight rating (GVWR) represent?

    Correct answer: Its manufacturer-specified loaded weight rating

    GVWR is a rating specified by the manufacturer, not the actual scale reading for a particular trip.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.2.1, Definitions You Should Know > Gross Vehicle Weight Rating; printed p. 3-2, physical PDF page 84. ↗

  21. Where should the heaviest cargo generally be placed to reduce rollover risk?

    Correct answer: As low as possible

    A lower center of gravity improves stability, especially in curves and emergency maneuvers.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.2.3, Do Not Be Top-heavy; printed p. 3-2, physical PDF page 84. ↗

  22. What can result from placing too little weight on the front axle?

    Correct answer: Reduced steering control

    Insufficient front-axle weight can reduce steering control.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.2.4, Balance the Weight; printed p. 3-2, physical PDF page 84. ↗

  23. Under federal rules for an interstate truck load, what minimum aggregate working load limit must tiedowns securing an article provide?

    Correct answer: At least half the secured article's weight

    The counted aggregate must be at least half the secured article's weight. Count half a tiedown's rating when it runs directly to the cargo or returns to the same vehicle side, and its full rating when it passes over, through or around the cargo to the opposite side. Additional cargo-specific requirements can apply.

    Source: 49 CFR 393.106(a) and (d)(1)-(3), applicability and aggregate working load limit; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.3.2, Cargo Tie-Down: working load limit; printed p. 3-3, physical PDF page 85. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=85 ↗

  24. An interstate truck carries a 7-foot article under the general federal tiedown rule. It is not blocked against forward movement. What is the minimum tiedown count?

    Correct answer: Two

    An article longer than 5 feet and no longer than 10 feet needs at least two tiedowns when it is not blocked against forward movement. Required working load limit and any cargo-specific rules still apply.

    Source: 49 CFR 393.110(a), (b)(2)(ii), and (d), general tiedown minimum and special-purpose exception; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.3.2, Cargo Tie-Down: tiedown count; printed p. 3-3, physical PDF page 85. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=85 ↗

  25. Why should a driver check cargo covers in the mirrors while traveling?

    Correct answer: A loose cover can tear away, expose cargo, or block someone's view

    A flapping cover can detach and create a visibility or roadway hazard.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.3.4, Covering Cargo; printed p. 3-3, physical PDF page 85. ↗

  26. You must back into an unfamiliar loading space. What should you do before beginning the maneuver?

    Correct answer: Get out and examine the planned path, including side and overhead clearance

    Inspect the complete path before backing. Walking around lets you identify hazards and clearances that may not be visible from the driving position.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.2.4, Backing Safely > Look at Your Path; printed p. 2-12, physical PDF page 41. ↗

  27. While backing slowly, you become unsure whether the right rear corner will clear an obstacle. What is the safest next step?

    Correct answer: Stop, secure the vehicle and get out to check the path

    If you are unsure of the path or clearance, stop and check it from outside the vehicle. Mirrors have blind spots, and moving slowly does not make uncertain clearance safe.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.2.4, Backing Safely > Use Traffic Monitoring Devices / Mirrors on Both Sides; printed p. 2-12, physical PDF page 41. ↗

  28. Before backing with a helper, which signal should you both agree on?

    Correct answer: A clear stop signal

    Keep the helper visible and agree on understood hand signals before backing. A clear stop signal is especially important.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.2.4, Backing Safely > Use a Helper When You Can; printed p. 2-13, physical PDF page 42. ↗

  29. The drive wheels begin spinning as you accelerate from a stop on a snowy road. What response does the handbook recommend?

    Correct answer: Ease off the accelerator to stop the wheel spin

    Too much power on a low-traction surface can make the drive wheels spin and cause loss of control. Remove your foot from the accelerator and use gradual acceleration suited to the available traction.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.2.1, Accelerating; printed p. 2-12, physical PDF page 41. ↗

  30. You are approaching a curve in a commercial vehicle with a manual transmission. When should you reduce speed and select the appropriate lower gear?

    Correct answer: Before entering the curve

    Slow to a safe speed and select the proper gear before the curve. This helps you maintain stable control rather than needing a gear change during the turn.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.3.1, Manual Transmissions > Before Entering a Curve; printed p. 2-14, physical PDF page 43. ↗

  31. A vehicle appears small and distant in your convex mirror. What should you remember before judging the available gap?

    Correct answer: The vehicle can be closer than its mirror image suggests

    Convex mirrors provide a wider view, but objects appear smaller and farther away than they really are. Allow for this distortion when judging traffic position.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.4.2, Seeing to the Sides and Rear > How to Use Traffic Monitoring Devices / Mirrors; printed p. 2-16, physical PDF page 45. ↗

  32. Before a trip with a trailer, which position allows an accurate check of mirror adjustment?

    Correct answer: With the tractor and trailer aligned straight

    Check mirror adjustment before the trip with the trailer straight. Showing part of your own vehicle provides a reference for judging other objects in the mirrors.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.4.2, Seeing to the Sides and Rear > Traffic Monitoring Devices / Mirrors Adjustment; printed p. 2-16, physical PDF page 45. ↗

  33. You are looking 12 to 15 seconds ahead as recommended for commercial driving. How should you also monitor the nearer road?

    Correct answer: Shift attention between distant and nearby conditions

    Looking well ahead does not replace monitoring nearby hazards. The handbook describes shifting attention back and forth between near and far to maintain awareness.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.4.1, Seeing Ahead > How Far Ahead to Look; printed p. 2-15, physical PDF page 44. ↗

  34. What is the safest way to make routine mirror checks while traveling?

    Correct answer: Use brief checks and return attention to the road ahead

    Frequent, brief mirror checks help you monitor surrounding traffic without traveling a long distance while looking away from the road ahead.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.4.2, Seeing to the Sides and Rear > How to Use Traffic Monitoring Devices / Mirrors; printed p. 2-16, physical PDF page 45. ↗

  35. Before departure, why should you secure loose tools and other articles in the cab?

    Correct answer: They can obstruct controls or strike occupants during a collision

    Loose articles can interfere with vehicle controls or become impact hazards. Secure them before driving rather than relying on their current resting position.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.5, Seven-step Inspection Method > Step 6 > Get In Vehicle; printed p. 2-10, physical PDF page 39. ↗

  36. A following driver wants to pass your truck. Should you wave them around as a guarantee that the road is clear?

    Correct answer: No, let that driver make their own safe passing decision

    Do not direct other traffic into a pass; you cannot guarantee the maneuver will remain safe.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.5.1, Signal Your Intentions > Do Not Direct Traffic; printed p. 2-17, physical PDF page 46. ↗

  37. For an interstate CMV breakdown that requires emergency warning devices, what is the latest deadline for placing them?

    Correct answer: Within 10 minutes

    Activate the flashers immediately and place the required devices as soon as possible, no later than ten minutes. The deadline is not a reason to delay.

    Source: 49 CFR 392.22(a), (b)(1), and (b)(2), immediate flashers, ten-minute deadline and exceptions; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.5.2, Communicating Your Presence > When Parked at the Side of the Road: warning-device deadline; printed p. 2-18, physical PDF page 47. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=47 ↗

  38. An interstate truck breaks down on a straight divided highway with clear sightlines. What federal warning-device layout applies?

    Correct answer: Within 10 feet, then about 100 and 200 feet toward approaching traffic

    Put the nearest device on the truck's traffic side within 10 feet of its rear, and the others about 100 and 200 feet toward approaching traffic in the occupied lane or shoulder. Obstructed-view situations require additional placement care.

    Source: 49 CFR 392.22(b)(2)(iv)-(v), obstructed views and divided or one-way roads; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.5.2, Communicating Your Presence > one-way/divided highway; Figure 2.8; printed p. 2-18, physical PDF page 47. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=47 ↗

  39. An interstate truck breaks down on a straight rural two-way highway. Why place required warning devices both ahead and behind?

    Correct answer: Traffic can approach the stopped vehicle from either direction

    Traffic approaches from both directions. The federal layout has a device about 100 feet in each direction and one on the traffic side about 10 feet toward approaching traffic. Hills, curves and other obstructions require different placement.

    Source: 49 CFR 392.22(b)(1)(i)-(iii) and (b)(2)(iv), two-direction layout and obstructed-view exception; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.5.2, Communicating Your Presence > two-way/undivided highway; Figure 2.9; printed p. 2-18, physical PDF page 47. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=47 ↗

  40. At dusk in rain, are identification and clearance lights alone sufficient to make your truck visible?

    Correct answer: No, use headlights too

    Clearance lamps do not replace headlights in reduced visibility.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.5.2, Communicating Your Presence > When It Is Hard to See; printed p. 2-17, physical PDF page 46. ↗

  41. You keep your hands on the wheel but become absorbed in a stressful conversation. What type of distraction can this create?

    Correct answer: Mental distraction from driving

    Attention can leave the driving task even when your eyes and hands appear correctly positioned.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.9.3, Types of Distractions > Mental distraction; printed p. 2-29, physical PDF page 58. ↗

  42. When is the best time to program the route into your navigation system?

    Correct answer: Before beginning to drive

    Plan and set up navigation before moving rather than divide attention in traffic.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.9.6, Don't Drive Distracted: maps, GPS and route planning; printed p. 2-31, physical PDF page 60. ↗

  43. A car ahead drifts within its lane while its driver looks down repeatedly. How should you react?

    Correct answer: Leave extra room and anticipate an unexpected movement

    Recognizing distraction in another driver helps you protect your own space.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.9.7, Watch Out for Other Distracted Drivers; printed p. 2-31, physical PDF page 60. ↗

  44. An aggressive driver tries to provoke you. What is the safer response?

    Correct answer: Create separation and avoid challenging the driver

    Do not turn another driver’s aggression into a contest.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.10.3, What You Should Do When Confronted by an Aggressive Driver; printed p. 2-31, physical PDF page 60. ↗

  45. Snow covers the truck's mirrors and side windows before departure. What is needed for a safe start?

    Correct answer: Clear them as well as the windshield

    You need usable views around the vehicle before entering traffic.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.13.1, Vehicle Checks > Windows and Traffic Monitoring Devices / Mirrors; continued physical 65, printed 2-36; printed p. 2-35, physical PDF page 64. ↗

  46. Why is a leaking exhaust especially dangerous when the cab windows are closed?

    Correct answer: Carbon monoxide may accumulate in the cab

    Check exhaust defects; a closed cab can retain poisonous exhaust gases.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.13.1, Vehicle Checks > Exhaust System; printed p. 2-36, physical PDF page 65. ↗

  47. After water enters a truck’s brakes, what behavior can occur?

    Correct answer: Weak, uneven, or grabbing brake action

    Water can change braking behavior and contribute to wheel lock or pulling.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.13.2, Driving > Wet Brakes; printed p. 2-36, physical PDF page 65. ↗

  48. A properly inflated tire’s pressure rises during hot-weather operation. Should you bleed air to its cold-pressure reading?

    Correct answer: No, it could become underinflated when it cools

    Heat raises pressure; follow cold-inflation specifications rather than vent hot tires.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.14.1, Vehicle Checks > Tires; printed p. 2-36, physical PDF page 65. ↗

  49. During a hot-weather stop, a tire is too hot to touch. What does the handbook direct you to do?

    Correct answer: Remain stopped until it cools

    Continuing with an overheated tire increases the risk of failure or fire.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.14.1, Vehicle Checks > Tires; printed p. 2-36, physical PDF page 65. ↗

  50. When is it safe to open the pressurized radiator system for a coolant check?

    Correct answer: After it has cooled, following the vehicle’s instructions

    Hot pressurized coolant can cause severe burns. Engine shutdown alone does not release that danger.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.14.1, Vehicle Checks > Engine Coolant; printed p. 2-37, physical PDF page 66. ↗

  51. Dark patches of tar have risen to the road surface in extreme heat. What hazard should you expect?

    Correct answer: Reduced traction on the slick patches

    Heat-softened surface tar can be slippery.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.14.2, Driving > Watch for Bleeding Tar; printed p. 2-37, physical PDF page 66. ↗

  52. How should a manual-transmission truck cross railroad tracks?

    Correct answer: Choose the gear before crossing; do not shift on tracks

    Avoid a missed shift or loss of movement where a train could approach.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.15.5, Crossing the Tracks; printed p. 2-39, physical PDF page 68. ↗

  53. One train has passed a crossing with two tracks. What must you check before proceeding?

    Correct answer: Whether another train is approaching on either track

    A train can conceal another train. Obey warning devices and verify the crossing is clear.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.15.3, Driving Procedures > Double Tracks Require a Double Check; printed p. 2-39, physical PDF page 68. ↗

  54. A railroad crossing has no active lights or gates. What does that mean for your decision?

    Correct answer: You must look and listen and determine that crossing is safe

    The absence of active warning equipment does not mean no train is coming. Look and listen, make sure there is room to clear the tracks, and obey any applicable stopping requirement.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.15.1, Types of Crossings > Passive Crossings; also physical 68, printed 2-39, 2.15.4; printed p. 2-37, physical PDF page 66. ↗

  55. Why is listening for a horn alone an unsafe crossing check?

    Correct answer: Cab noise may hide the horn until the train is dangerously close

    Do not depend on hearing a horn. Check for trains and obey crossing controls before proceeding.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.15.3, Driving Procedures > Do Not Expect to Hear a Train; printed p. 2-39, physical PDF page 68. ↗

  56. The front wheels slide and the truck continues straight despite steering input. What should you avoid?

    Correct answer: Adding more harsh steering or braking

    A front-wheel skid needs traction recovery; greater steering force does not create grip.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.19.3, Front-wheel Skids; printed p. 2-45, physical PDF page 74. ↗

  57. Excessive braking has locked the rear drive wheels of a truck without effective ABS intervention. What is the first recovery action?

    Correct answer: Stop braking so the wheels can roll again

    Restore rolling traction before completing the steering correction. This is not normal ABS braking advice.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.19.2, Correcting a Drive-wheel Braking Skid; ABS distinction physical 73, printed 2-44, 2.18.6; printed p. 2-45, physical PDF page 74. ↗

  58. After a collision, you are uninjured and able to act. What is an immediate priority?

    Correct answer: Prevent another collision at the scene

    Protect the area, request assistance, and keep emergency access clear.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.20.1, Protect the Area; printed p. 2-46, physical PDF page 75. ↗

  59. You stop to help at a collision in which your truck was not involved. Where should you park?

    Correct answer: Away from the immediate scene so emergency vehicles have space

    Helping should not obstruct rescuers or create a second hazard.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.20.1, Protect the Area: parking when stopping to help; printed p. 2-46, physical PDF page 75. ↗

  60. Smoke indicates a vehicle fire while you are driving. Where should you stop if you can safely move off the road?

    Correct answer: An open area clear of combustible surroundings

    Stop safely away from things that could ignite and notify emergency services.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.21.3, Fire Fighting > Pull Off the Road; printed p. 2-47, physical PDF page 76. ↗

  61. Why should you avoid opening the hood during an engine fire?

    Correct answer: It can feed oxygen to the fire

    Shut the engine off when safe and avoid actions that intensify the fire.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.21.3, Fire Fighting > Keep the Fire from Spreading; printed p. 2-47, physical PDF page 76. ↗

  62. Smoke comes from a closed box trailer, and the cargo may be hazardous. Should you open its doors to investigate?

    Correct answer: No, keep them closed and summon emergency help

    Opening the doors can rapidly feed a cargo fire; unknown hazardous cargo adds further danger.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.21.3, Fire Fighting > Keep the Fire from Spreading: cargo fire; printed p. 2-47, physical PDF page 76. ↗

  63. For a small fire you are trained to tackle safely, with the correct extinguisher and a clear escape path, where should you aim?

    Correct answer: At the base of the fire

    The extinguishing agent must reach the burning material rather than only the rising flames.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.21.3, Fire Fighting > Extinguish the Fire; printed p. 2-47, physical PDF page 76. ↗

  64. You do not know which extinguishing agent is safe for the burning cargo. What should you do?

    Correct answer: Stay clear and wait for trained firefighters

    An unsuitable agent can worsen a fire, especially when hazardous materials are involved.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.21.3, Fire Fighting > Use the Right Fire Extinguisher: uncertainty about the agent; printed p. 2-47, physical PDF page 76. ↗

  65. A B:C extinguisher is intended for which hazards?

    Correct answer: Flammable-liquid and electrical fires

    Match the rating to the fire; do not assume one extinguisher covers every material.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.21.3, Fire Fighting > Use the Right Fire Extinguisher: B:C prose; printed p. 2-47, physical PDF page 76. ↗

  66. What is the purpose of blocks secured snugly around cargo?

    Correct answer: Prevent the cargo from sliding

    Blocking restrains movement rather than merely filling unused cargo space.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.3.1, Blocking and Bracing: blocking; printed p. 3-3, physical PDF page 85. ↗

  67. What does bracing between upper cargo and the compartment structure help prevent?

    Correct answer: Movement of the load

    Bracing is part of the load-restraint system, not a substitute for inspections.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.3.1, Blocking and Bracing: bracing; printed p. 3-3, physical PDF page 85. ↗

  68. Your load uses a front-end header board for forward restraint. Why inspect that board before departure?

    Correct answer: It helps restrain forward cargo movement toward the cab

    A sound front-end structure helps restrain forward cargo movement during a sudden stop. It does not replace the other securement that the load needs.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.3.3, Header Boards; printed p. 3-3, physical PDF page 85. ↗

  69. An interstate truck carries a sealed load that you are ordered not to open. Which duty still remains?

    Correct answer: Check compliance with gross and axle weight limits

    The sealed-load inspection exception does not waive gross or axle weight limits. Check those limits without treating the seal as proof that the vehicle is not overloaded.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.3.5, Sealed and Containerized Loads; printed p. 3-3, physical PDF page 85. Corroboration/qualification: 49 CFR 392.9(b)(4), https://www.ecfr.gov/current/title-49/subtitle-B/chapter-III/subchapter-B/part-392/subpart-A/section-392.9, reviewed 2026-09-12. ↗

  70. What makes a dry-bulk tank load demanding in a sharp curve?

    Correct answer: A high center of gravity and possible load movement

    Reduce speed before curves and avoid abrupt maneuvers.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.4.1, Dry Bulk; printed p. 3-4, physical PDF page 86. ↗

  71. Why is suspended meat cargo a special concern on an off-ramp?

    Correct answer: It can swing and make a high load unstable

    The suspended load calls for conservative cornering speed.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.4.2, Hanging Meat; printed p. 3-4, physical PDF page 86. ↗

  72. How can live animals affect trailer stability?

    Correct answer: Their movement can shift the center of gravity

    Moving livestock remains a handling concern even when the load is contained.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.4.3, Livestock; printed p. 3-4, physical PDF page 86. ↗

  73. Before moving a load that exceeds ordinary legal size or weight limits, what arrangements should you check?

    Correct answer: Permits, routing limits, and required warnings or escorts

    Determine the applicable permit, route, time and warning or escort requirements before departure. Do not assume a warning sign alone authorizes the movement.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.4.4, Oversized Loads; printed p. 3-4, physical PDF page 86. ↗

  74. What does axle weight measure?

    Correct answer: Weight transmitted to the ground by an axle or axle group

    Axle loading is a separate limit from the vehicle’s total gross weight.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.2.1, Definitions You Should Know > Axle Weight; printed p. 3-2, physical PDF page 84. ↗

  75. Your load is within the legal maximum. Does that guarantee it is safe for bad weather or a mountain route?

    Correct answer: No, conditions can require operating below legal maximum weight

    Legal limits do not replace judgment about braking, traction, and the route.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.2.2, Legal Weight Limits; printed p. 3-2, physical PDF page 84. ↗

  76. How should you determine suitable shift points for an unfamiliar commercial vehicle?

    Correct answer: Learn its specified engine-speed and road-speed ranges

    Shift patterns and useful rpm ranges vary between vehicles.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.3.1, Manual Transmissions > Knowing When to Shift Up; printed p. 2-13, physical PDF page 42. ↗

  77. Why does the handbook advise turning a retarder off on a slippery road?

    Correct answer: Its drive-wheel braking can cause a skid

    A retarder acts through the drive wheels; reduced grip can make that braking unsafe.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.3.4, Retarders > Caution; printed p. 2-14, physical PDF page 43. ↗

  78. An approaching driver leaves bright lights on. What should you do?

    Correct answer: Look toward the right edge reference without staring into the glare

    Avoid adding glare or losing sight of your own lane; reduce speed when needed.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.11.5, Night Driving Procedures > Avoid Glare from Oncoming Vehicles; printed p. 2-34, physical PDF page 63. ↗

  79. Why clean both sides of the windshield before a night trip?

    Correct answer: Dirt can scatter light and worsen glare

    Interior film as well as exterior dirt can obscure the road under bright lights.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.11.4, Vehicle Factors > Windshield and Traffic Monitoring Device / Mirror; printed p. 2-34, physical PDF page 63. ↗

  80. Your eyelids are heavy and you are struggling to stay alert. What is the safe response?

    Correct answer: Stop at a safe place and sleep

    Temporary stimulation does not replace sleep or make continued drowsy driving safe.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.11.5, Night Driving Procedures > If You Get Sleepy, Stop at the Nearest Safe Place; fatigue guidance physical 62, printed 2-33; printed p. 2-35, physical PDF page 64. ↗

  81. You see dense fog ahead while approaching a safe truck stop. What is the preferable choice?

    Correct answer: Leave the roadway safely and wait for visibility to improve

    A safe off-road waiting area is preferable to entering severely limited visibility.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.12, Driving in Fog; printed p. 2-35, physical PDF page 64. ↗

  82. Why should you avoid using another vehicle’s taillights as your only guide through fog?

    Correct answer: That vehicle may be stopped off the roadway

    Identify your own road path and leave enough distance rather than blindly following lights.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.12, Driving in Fog: lights on vehicles off the roadway; printed p. 2-35, physical PDF page 64. ↗

  83. When should you learn how to fit the chains carried for your drive tires?

    Correct answer: Before encountering conditions that require them

    Check fit and condition in advance so the equipment can be used correctly when required.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.13.1, Vehicle Checks > Tire Chains; printed p. 2-35, physical PDF page 64. ↗

  84. Which combination matters when selecting a safe descent speed?

    Correct answer: Vehicle weight, grade length and steepness, road and weather

    Different loads and grades can demand different descent speeds even under the same posted limit.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.16.1, Select a Safe Speed; printed p. 2-40, physical PDF page 69. ↗

  85. Your truck’s brakes have failed on a downgrade and an escape ramp is available. What should you do?

    Correct answer: Use the escape ramp

    A designated escape ramp offers a means to stop a runaway vehicle; delay increases danger.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.17.3, Brake Failure > Brake Failure on Downgrades; printed p. 2-42, physical PDF page 71. ↗

  86. A hydraulic service-brake pedal goes to the floor. Which action may briefly restore hydraulic pressure?

    Correct answer: Pump the brake pedal while seeking a safe way to stop

    This is a hydraulic-pressure-loss technique, not normal ABS braking or an air-brake recovery method. Use other appropriate emergency measures and stop.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.17.3, Brake Failure > Loss of Hydraulic Pressure; printed p. 2-42, physical PDF page 71. ↗

  87. A truck tire fails, but there is no immediate collision ahead. What is the initial response?

    Correct answer: Hold steering firmly; coast before gentle braking

    Control the vehicle first, then brake gently and stop safely for an inspection.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.17.4, Tire Failure > Respond to Tire Failure; printed p. 2-43, physical PDF page 72. ↗

  88. Does buying a cold medicine without a prescription prove it is safe before commercial driving?

    Correct answer: No, it may cause drowsiness or impair driving

    Check warnings and appropriate medical advice; over-the-counter availability is not a safety guarantee.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.22.2, Other Drugs: over-the-counter medicines and warning labels; printed p. 2-49, physical PDF page 78. ↗

  89. A cardboard box in your lane looks empty. What should you remember when planning how to avoid it?

    Correct answer: It may conceal a solid or heavy object

    A harmless-looking box or sack may contain something that damages tires, wheels or other parts. Look far enough ahead to avoid debris without a sudden, unsafe maneuver.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.8.2, Hazardous Roads > Foreign Objects; printed p. 2-26, physical PDF page 55. ↗

  90. Why should a commercial driver keep required hazardous-material shipping papers easy to find?

    Correct answer: Responders may need to identify the cargo when the driver cannot speak

    Accessible cargo information helps emergency personnel choose suitable precautions.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.23.2, Why Are There Rules? > To Communicate the Risk: shipping papers; printed p. 2-51, physical PDF page 80. ↗

  91. Your vehicle was operating normally yesterday. What inspection is needed for the next trip?

    Correct answer: Inspect it before operating, including working clean lights and cargo securement

    A routine before-trip inspection can reveal new defects. Check the required vehicle components and load; yesterday’s condition is not proof of today’s safety.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.2, Types of Vehicle Inspection > Pre-trip Inspection; walkaround physical 36-39, printed 2-7 through 2-10; printed p. 2-2, physical PDF page 31. ↗

  92. A hot engine has a see-through coolant reservoir with level markings. How can you check the level without opening the hot system?

    Correct answer: Read the level through the reservoir wall while leaving the pressure cap closed

    A sight glass or transparent reservoir allows a visual check. Never open a hot pressurized cooling system.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.14.1, Vehicle Checks > Engine Coolant: sight glasses and see-through containers; printed p. 2-37, physical PDF page 66. ↗

  93. An interstate truck breaks down on a highway shoulder. Which lights should you switch on immediately?

    Correct answer: The four-way emergency flashers

    Four-way flashers warn approaching traffic that the vehicle is stopped. If warning devices are required, place them promptly too; flashers are not a substitute.

    Source: 49 CFR 392.22(a), immediate hazard flashers for highway or shoulder stops other than necessary traffic stops; eCFR Title 49 current through 2026-09-10, reviewed 2026-09-12. Interstate CMV scope. Related PA study passage: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.5.2, Communicating Your Presence > When Parked at the Side of the Road; printed p. 2-17, physical PDF page 46. https://www.pa.gov/content/dam/copapwp-pagov/en/penndot/documents/public/dvspubsforms/bdl/bdl-manuals/commercial-drivers-manual/pub223.pdf#page=46 ↗

  94. In its basic steering-defect guidance, what amount of steering-wheel free play does the Pennsylvania CDL manual warn can make steering difficult?

    Correct answer: More than 10 degrees

    The manual warns about more than 10 degrees of play. This is inspection guidance, not one universal regulatory limit: federal steering-lash limits vary with wheel diameter and steering-system type.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.1.3, What to Look For > Steering System Defects; printed p. 2-3, physical PDF page 32. Corroboration/qualification: 49 CFR 393.209(b), https://www.ecfr.gov/current/title-49/subtitle-B/chapter-III/subchapter-B/part-393/subpart-J/section-393.209, reviewed 2026-09-12. ↗

  95. A freight container is designed to transfer between a truck chassis, a train and a ship. What kind of container is it?

    Correct answer: An intermodal container

    Intermodal means the container can be used across two or more transport modes; the cargo still needs appropriate securement.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.3.5, Sealed and Containerized Loads; printed p. 3-3, physical PDF page 85. Corroboration/qualification: 393.126 - Intermodal Containers, https://www.fmcsa.dot.gov/regulations/cargo-securement/cargo-securement-rules, reviewed 2026-09-12. ↗

  96. Why should a driver not use water on burning gasoline or energized electrical equipment?

    Correct answer: It can spread burning gasoline or create an electrical-shock hazard

    Use a suitable extinguishing agent only when safe and trained to do so. Withdraw and get emergency help if the fire or material is uncertain.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.21.3, Fire Fighting > Use the Right Fire Extinguisher: water limitations; printed p. 2-47, physical PDF page 76. ↗

  97. Which three distances make up the basic stopping-distance model in Pennsylvania CDL manual section 2.6.1?

    Correct answer: Perception, reaction and braking distances

    The vehicle travels while you recognize a hazard, while you respond, and while the brakes slow it to a stop. This question concerns the basic model, not the separate air-brake discussion.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.6.1, Stopping Distance: basic three-part model; printed p. 2-19, physical PDF page 48. ↗

  98. A newer streamlined truck climbed a hill in a relatively high gear. Should you automatically use that same gear to descend?

    Correct answer: No, the descent may require a lower gear suited to that truck and grade

    Reduced drag and different engine performance can make the old same-gear rule unsuitable. Select the correct low gear before descending.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.16.2, Select the Right Gear Before Starting Down the Grade; printed p. 2-40, physical PDF page 69. ↗

  99. Two legal parking spaces are equally suitable for your truck. One allows a forward exit; the other requires backing into traffic. Which is preferable?

    Correct answer: The space that allows you to pull forward when leaving

    Plan parking to avoid reversing when possible because you cannot see everything behind a large vehicle.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 2.2.4, Backing Safely: avoiding backing; printed p. 2-12, physical PDF page 41. ↗

  100. Why check the rated capacity of a coupling device before assigning a load?

    Correct answer: It has limits on the weight it can pull or carry

    A coupling has its own rated limit for weight pulled or carried. Check that rating along with the vehicle, axle, tire and applicable legal limits.

    Source: Pennsylvania Commercial Driver's Manual PUB 223 (6-26), 3.2.1, Definitions You Should Know > Coupling Device Capacity; printed p. 3-2, physical PDF page 84. ↗

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Pennsylvania CDL: General Knowledge

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